A pseudo-outbreak of MRSA due to laboratory contamination related to MRSA carriage of a laboratory staff member.

BACKGROUND: Methicillin resistant Staphylococcus aureus (MRSA) is a major burden for hospitals globally. However, in the Netherlands, the MRSA prevalence is relatively low due to the 'search and destroy' policy. Routine multiple-locus variable-number of tandem repeat analysis (MLVA) of MRSA isolates supports outbreak detection. However, whole genome multiple locus sequence typing (wgMLST) is superior to MLVA in identifying (pseudo-)outbreaks with MRSA. The present study describes a pseudo-outbreak of MRSA at the bacteriology laboratory of a large Dutch teaching hospital. METHODS: All staff members of the bacteriology laboratory of the Elisabeth-TweeSteden hospital were screened for MRSA carriage, after a laboratory contamination with MRSA was suspected. Clonal relatedness between the index isolate and the MRSA isolates from laboratory staff members and all previous MRSA isolates from the Elisabeth-TweeSteden hospital with the same MLVA-type as the index case was examined based on wgMLST using whole genome sequencing. RESULTS: One of the staff members was identified as the probable source of the laboratory contamination, because of carriage of a MRSA possessing the same MLVA-type as the index case. Eleven other isolates with the same molecular characteristics were found in the database, of which seven were retrospectively suspected of contamination. Clonal relatedness was found between ten isolates, including the isolate found in the staff member and the MRSA found in the index patient with a maximum of eleven alleles difference. All isolates were epidemiologically linked through the laboratory staff member, who had worked on all these cultures. CONCLUSIONS: The present study describes a MRSA pseudo-outbreak over a 2.5-year period due to laboratory contamination caused by a MRSA carrying laboratory staff member involving nine patients. In case of unexpected bacteriological findings, the possibility of a laboratory contamination should be considered.

Concomitant endocarditis and spondylodiscitis due to coagulase-negative Staphylococci and a review of the literature.

BACKGROUND: Coagulase-negative staphylococci (CoNS) are part of the normal skin flora. Although CoNS are generally considered as low pathogenic microorganisms, they can cause serious infections, particularly in the context of foreign body material. CASE REPORT: Here we present two cases of concomitant infectious endocarditis and spondylodiscitis; one caused by S. epidermidis, the other by S. haemolyticus. Additionally, we reviewed the literature for previously reported cases of concomitant endocarditis and spondylodiscitis due to CoNS. CONCLUSION: In patients with back pain and a cardiac device in situ, CoNS should be considered as causative pathogens for possible endocarditis and/or spondylodiscitis, and should not be regarded as contamination.